Low inductance bus assembly and power converter apparatus including the same

ABSTRACT

An apparatus, such as a power converter, includes first, second and third core bus plates arranged in parallel. The apparatus also includes a first bus extension plate joined to the first core bus plate and extending therefrom at a first angle and a second bus extension plate joined to the second core bus plate and extending therefrom at a second angle. The apparatus further includes a third bus extension plated joined with the third core bus plate and disposed parallel to the first bus extension plate and a fourth bus extension plate joined with the third core bus plate and disposed parallel to the second bus extension plate.

BACKGROUND

The inventive subject matter relates to power conversion apparatus and,more particularly, to power converter bus structures and power convertersystems incorporating the same.

Conventional power converter apparatus commonly use silicon-basedsemiconductor switching devices, such as insulated gate bipolartransistors (IGBTs). Such devices are typically limited to operatingvoltages less than 10 kV and switching frequencies less than 100 kHz.For applications requiring higher operating voltages and frequencies,wide bandgap semiconductor switching devices, such as silicon carbide(SiC) MOSFETs, have been developed to replace conventional siliconIGBT-based solutions.

Wide bandgap semiconductor switching devices may be operated atfrequencies on the order of 20 times greater than the maximum operatingfrequencies of conventional silicon IGBTs. At these higher switchingspeeds, circuit parasitics, such as parasitic inductance and capacitanceassociated with interconnecting bus bars, can cause significant voltageand current transients that can be detrimental to operation of a powerconverter and limit full utilization of the capabilities of these higherperformance devices.

SUMMARY OF THE INVENTION

Some embodiments of the inventive subject matter provide an apparatusincluding first, second and third core bus plates arranged in parallel.The apparatus also includes a first bus extension plate joined to thefirst core bus plate and extending therefrom at a first angle and asecond bus extension plate joined to the second core bus plate andextending therefrom at a second angle. The apparatus further includes athird bus extension plated joined with the third core bus plate anddisposed parallel to the first bus extension plate and a fourth busextension plate joined with the third core bus plate and disposedparallel to the second bus extension plate.

In some embodiments, the third core bus plate may be disposed betweenthe first and second core bus plates. The first bus extension plate mayextend from the first core bus plate in a first direction perpendicularto a plane of the first core bus plate and the second bus extensionplate may extend from the second core bus plate in a second directionopposite the first bus direction. The third bus extension plate mayextend from the third core bus plate in the first direction and thefourth bus extension plate may extend from the third core bus plate inthe second direction.

In further embodiments, the first bus extension plate may include afirst planar member that joins the first core bus plate at a firstarcuate joint. The second bus extension plate may include a secondplanar member that joins the second core bus plate at a second arcuatejoint. The third and fourth bus extension plates may include third andfourth planar members that join the third core bus plate at a rounded Yjoint.

According to some embodiments, the first bus extension plate may jointhe first core bus plate at a first edge thereof and the second busextension plate may join the second core bus plate at a first edgethereof. The apparatus may further include a fifth bus extension platejoining the first core bus plate at a second edge thereof and extendingtherefrom at a third angle, a sixth bus extension plate joining thesecond core bus plate at a second edge thereof and extending therefromat a fourth angle, a fourth core bus plate disposed in parallel with thefirst, second and third core bus plates, a seventh bus extension platejoined to the fourth core bus plate and disposed parallel to the fifthbus extension plate, and an eighth bus extension plate joined to thefourth core bus plate and disposed parallel to the sixth bus extensionplate. The first and fifth bus extension plates may extend from thefirst core bus plate in a first direction perpendicular to a plane ofthe first core bus plate and the second and sixth bus extension platesmay extend from the second core bus plate in a second direction oppositethe first direction. The third and fourth core bus plates may bedisposed between the first and second core bus plates.

The apparatus may further include a ninth bus extension plate joiningthe first core bus plate at a third edge thereof and extending therefromat a fifth angle, a tenth bus extension plate joining the second corebus plate at a third edge thereof and extending therefrom at a sixthangle, a fifth core bus plate arranged in parallel with the first,second, third and fourth core bus plates, an eleventh bus extensionplate joined to the fifth core bus plate and disposed parallel to theninth bus extension plate, and a twelfth bus extension plate joined tothe fifth core bus plate and disposed parallel to the tenth busextension plate. The first, fifth and ninth bus extension plates mayextend from the first core bus plate in the first direction and thesecond, sixth and tenth bus extension plates may extend perpendicularlyfrom the second core bus plate in the second direction. The third,fourth and fifth core bus plates may be disposed between the first andsecond core bus plates.

According to some aspects, the apparatus may further include a firstsemiconductor switching device electrically connected to ends of thefirst and third bus extension plates and a second semiconductorswitching device electrically connected to ends of the second and fourthbus extension plates. The apparatus may include a power convertercircuit including the first and second semiconductor devices, whereinthe first core bus plate and the first bus extension plate arecomponents of a first DC bus of the power converter circuit, wherein thesecond core bus plate the second bus extension plate are components of asecond DC bus of the power converter circuit, and wherein the third corebus plate, the third bus extension plate and the fourth bus extensionplate are components of an input bus and/or an output bus of the powerconverter circuit.

A first capacitor may be electrically connected to the first bus coreplate and a second capacitor may be electrically connected to the secondbus core plate. The apparatus may further include a fifth bus extensionplate joined to the first bus core plate, extending at an angletherefrom and electrically connected to a first terminal of the firstcapacitor, a sixth bus extension plate joined to the second bus coreplate, extending at an angle therefrom and electrically connected to afirst terminal of the second capacitor, and a common plate parallel tothe fifth and sixth bus extension plates and electrically connected tosecond terminals of the first and second capacitors, wherein the thirdbus core plate has a portion extending between the fifth and sixth busextension plates and through an opening in the common plate.

Further embodiments of the inventive subject matter provide an apparatusincluding first, second and third buses arranged in parallel, the thirdbus disposed between the first and second buses, a first bus extensionextending from the first bus in first direction perpendicular to thefirst bus, a second bus extension extending from the second bus in asecond direction perpendicular to the second bus and opposite the firstdirection, a third bus extension extending from the third bus inparallel with the first bus extension, and a fourth bus extensionextending from the third bus in parallel with the second bus extension.A first semiconductor switching device is coupled to an end of the firstbus extension and to an end of the third bus extension and a secondsemiconductor switching device is coupled to an end of the second busextension and to an end of the fourth bus extension.

The first, second and third buses may include respective first, secondand third planar members. The first bus extension may be joined to thefirst bus at a first edge of the first planar member, the second busextension may be joined to the second bus at a first edge of the secondplanar member, and the third and fourth bus extensions may be joined tothe third bus at a first edge of the third planar member. The apparatusmay further include a fourth bus including a fourth planar memberarranged in parallel with the first, second and third buses, a fifth busextension joined to the first bus at a second edge of the first planarmember extending from the first bus in the first direction, a sixth busextension joined to the second bus at a second edge of the second planarmember and extending from the second bus in the a second direction, aseventh bus extension joined to the fourth bus at a first edge of thefourth planar member and extending in parallel with the fifth busextension, and an eighth bus extension joined to the fourth bus at thefirst edge of the fourth planar member and extending in parallel withthe sixth bus extension. A third semiconductor switching device may becoupled to an end of the fifth bus extension and to an end of theseventh bus extension, and a fourth semiconductor switching device maybe coupled to an end of the sixth bus extension and to an end of theeighth bus extension.

Still further embodiments provide an apparatus including first andsecond semiconductor switching devices disposed opposite one another atrespective ones of opposing first and second surfaces, a first busincluding a first conductive plate disposed between the first and secondsurfaces and extending in a first direction towards the first surface toelectrically connect to the first semiconductor switching device, asecond bus including a second conductive plate disposed between thefirst and second surfaces and extending in a second directionperpendicular to the first direction towards the second surface toelectrically connect to the second semiconductor switching device, and athird bus including a third conductive plate disposed parallel to thefirst conductive plate and electrically connected to the firstsemiconductor switching device and a fourth conductive plate disposedparallel to the second conductive plate and electrically connected tothe second semiconductor switching device and the third conductiveplate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are perspective views illustrating a power converterapparatus according to some embodiments.

FIG. 3 is a perspective view of a bus assembly of the power converterapparatus of FIG. 1.

FIG. 4 is an isolated perspective view of a DC bus of the bus assemblyof FIG. 3.

FIG. 5 is an isolated perspective view of input/output buses of the busassembly of FIG. 3.

FIG. 6 is a detailed perspective view of core plates of the input/outputbuses of FIG. 4.

FIG. 7 is an isolated perspective view of one of the input/output busesof FIG. 3.

FIGS. 8 and 9 are detailed perspective views of connections of the busassembly and a power transistor module in the power converter apparatusof FIGS. 1 and 2.

FIG. 10 is a cutaway view illustrating connection of a DC bus to a powertransistor module in the power converter apparatus of FIGS. 1 and 2.

FIGS. 11-13 are perspective views of a power transistor module of thepower converter apparatus of FIGS. 1 and 2.

FIGS. 14-16 are perspective views of connection of a bus assembly tostorage capacitors in the power converter apparatus of FIGS. 1 and 2.

FIG. 17 is a schematic diagram illustrating a half-bridge circuit in thepower converter apparatus of FIGS. 1 and 2.

DETAILED DESCRIPTION

Specific exemplary embodiments of the inventive subject matter now willbe described with reference to the accompanying drawings. This inventivesubject matter may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventivesubject matter to those skilled in the art. In the drawings, likenumbers refer to like items. It will be understood that when an item isreferred to as being “connected” or “coupled” to another item, it can bedirectly connected or coupled to the other item or intervening items maybe present. As used herein the term “and/or” includes any and allcombinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the inventivesubject matter. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless expresslystated otherwise. It will be further understood that the terms“includes,” “comprises,” “including” and/or “comprising,” when used inthis specification, specify the presence of stated features, integers,steps, operations, items, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, items, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this inventive subject matterbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of thespecification and the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

FIGS. 1 and 2 illustrate a power converter apparatus 100 according tosome embodiments of the inventive subject matter. The apparatus 100includes semiconductor switching devices, here shown as power transistormodules 120, which are mounted on opposing parallel heat sinks 110. Eachof the modules 120 includes one or more power transistors. For example,each of the modules may include six power MOSFET transistors, which maybe connected in parallel to increase current capability. A bus assembly130 interconnects the modules 120 and includes first and second DC buses131, 132 and three input/output buses 133 (one per phase), whichinterconnect the transistor modules 120 to implement a three-phaseconverter including three half-bridge circuits, such as the half-bridgecircuit 1700 shown schematically in FIG. 17. It will be appreciated thatsuch a converter may be operated as an inverter, a rectifier or abidirectional converter.

As further illustrated in FIGS. 1 and 2, the converter apparatus 100also includes storage capacitors 140, which have first terminals coupledto respective ones of the DC busses 131, 132 and second terminalscoupled in common to a common bus 150. As explained in greater detailbelow, the DC buses 131, 132 and the input/output buses 133 areconfigured to provide low-inductance interconnections of the capacitors140 and the transistor modules 120, which can be particularlyadvantageous for applications in which the transistor modules 120include wide bandgap switching devices, such as Group III-V wide bandgapMOSFETs, that can be operated at high switching speeds and operatingvoltages.

FIGS. 3-7 illustrate details of the bus assembly 130. Referring to FIGS.3 and 4, the first DC bus 131 includes a core plate 131 a from whichfirst, second and third bus extension plates 131 b, 131 c, 131 d extendin a perpendicular fashion to connect to the transistor modules 120. Thefirst, second and third bus extension plates 131 b, 131 c, 131 d arejoined to the core plate 131 a by rounded, arcuate joints 131 e, 131 f,131 g, which can provide a more uniform current distribution and reducethe likelihood of arcing that can arise from the presences of sharpedges or similar features. Additional fourth and fifth bus extensionplates 131 h, 131 i extend laterally from the core plate 131 a toprovide connections to a DC source and/or load. It will be appreciatedthat the second DC bus 132 has a similar structure.

FIGS. 5-7 illustrate the structure of the input/output buses 133. Eachof the input/output buses 133 includes a core plate 133 a, from whichfirst and second bus extension plates 133 b, 133 c extendperpendicularly from the core plate 133 a in opposite first and seconddirections. The first and second bus extension plates 133 b, 133 c arejoined to the core plate 133 a at a rounded Y-cross section joint thatprovides arcuate junctions between the bus extension plates 133 b, 133 cand the core plate 133 a. As explained above, this configuration canimprove current distribution and reduce the likelihood of arcing.Referring to FIG. 6, the core plates 133 a of the input/output buses 133are arranged in parallel and separated by insulating material (notshown), resulting in composite input/output bus structure as shown inFIG. 5.

Referring again to FIG. 3, respective ones of the input/output busextension plates 133 b, 133 c are disposed parallel to and generallyconform to the contours of respective ones of the DC bus extensionplates 131 b, 132 b of the first and second DC buses 131, 132. As shownin FIGS. 1 and 2, ends of the parallel DC and input/output bus extensionplates 131 b, 133 c are electrically connected a first one of thetransistor modules 120, while ends of the parallel bus extension plates132 b, 133 b are electrically connected to a second one of thetransistor modules 120. The use of relatively wide, plate-type busconductors and close, conformal parallel routing of the ingoing andoutgoing buses connected to each transistor module 120 can reduce strayinductance in comparison to conventional designs. The symmetricalconfiguration of the bus structure 130 with respect to the capacitors140 can also provide substantially equal current sharing among thetransistors in the modules 120.

The DC buses 131, 132 and the input/output buses 133 can be providedwith additional features to, for example, achieve desirable currentdistribution characteristics and/or limit arcing at high operatingvoltages. For example, as shown in FIG. 1, lateral edges of the parallelDC bus extension plates 131 b, 132 b and the corresponding parallelinput/output bus extension plates 133 b, 133 c can be slightly offset toreduce the likelihood of arcing between these edges. The DC buses 131,132 and the input/output buses 133 can be fabricated using any of anumber of different techniques to achieve desired topological and otherfeatures. For example, in some embodiments, the DC buses 131, 132 andthe input/output buses 133 could be fabricated using three-dimensional(3D) printing techniques, such as direct metal laser sintering (DMLS),which can be used to introduce features such as variable thicknessregions, variable resistance regions, openings, meshes and the like.Such features may be used, for example, to achieve a desired currentdistribution and/or limit the likelihood of arcing between the buses andadjacent structures.

FIGS. 8-10 illustrate details of interconnections of the bus extensionplates to the transistor modules 120. First contacts 121 of a transistormodule 120 are contacted by a flange 135 at the end of the input/outputbus extension plate 133 c. Second contacts 122 of the transistor module120 are connected to the extension plate 131 b of the first DC bus 131.This contact arrangement can provided the connectivity illustrated inFIG. 17.

FIGS. 11-13 illustrate the mounting of the transistor module 120 on theheat sink 110. The base of the transistor module 120 is disposed on theheat sink 110, with a thermally conductive and electrically insulatingceramic pad 124 separating the transistor module 120 from the surface ofthe heat sink 110. Insulating ceramic clamps 123 on respective first andsecond sides of the transistor module 120 are used to secure thetransistor module 120 to the heat sink 110 without an electricalconnection between the transistor module 120 and the heatsink 110. Thisenables fabrication of the heatsink 110 from electrically conductivematerial (e.g., aluminum) and allows for grounding of the heatsink 110.The illustrated mounting arrangement using the insulating ceramic clamps123 can also reduce the likelihood of arcing between the terminals 121,122 of the transistor module 120 and adjacent metal structures in highvoltage applications.

FIGS. 14-16 illustrate details of the connection of the DC buses 131,132 to the capacitors 140 shown in FIGS. 1 and 2. As shown in FIG. 16,the DC buses 131, 132 have perpendicular bus extensions 131 j, 132 jthat are configured to be attached to first terminals 141 of thecapacitors 140. The common plate 150 is configured to be attached tosecond terminals of the capacitors 140. Bus extensions of theinput-output buses 133 pass through an opening in the common plate, ascan be seen in FIG. 15.

In the drawings and specification, there have been disclosed exemplaryembodiments of the inventive subject matter. Although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the inventive subject matterbeing defined by the following claims.

1. An apparatus comprising: first, second and third core bus platesarranged in parallel; a first bus extension plate joined to the firstcore bus plate and extending therefrom at a first angle; a second busextension plate joined to the second core bus plate and extendingtherefrom at a second angle; and a third bus extension plated joinedwith the third core bus plate and disposed parallel to the first busextension plate; and a fourth bus extension plate joined with the thirdcore bus plate and disposed parallel to the second bus extension plate.2. The apparatus of claim 1, wherein the third core bus plate isdisposed between the first and second core bus plates.
 3. The apparatusof claim 1: wherein the first bus extension plate extends from the firstcore bus plate in a first direction perpendicular to a plane of thefirst core bus plate; wherein the second bus extension plate extendsfrom the second core bus plate in a second direction opposite the firstbus direction; wherein the third bus extension plate extends from thethird core bus plate in the first direction; and wherein the fourth busextension plate extends from the third core bus plate in the seconddirection.
 4. The apparatus of claim 3, wherein the third and fourth busextension plates lie in the same plane.
 5. The apparatus of claim 3,wherein the first bus extension plate comprises a first planar memberthat joins the first core bus plate at a first arcuate joint, whereinthe second bus extension plate comprises a second planar member thatjoins the second core bus plate at a second arcuate joint and whereinthe third and fourth bus extension plates comprise third and fourthplanar members that join the third core bus plate at a rounded Y joint.6. The apparatus of claim 1, wherein the first bus extension plate joinsthe first core bus plate at a first edge thereof and wherein the secondbus extension plate joins the second core bus plate at a first edgethereof, and wherein the apparatus further comprises: a fifth busextension plate joining the first core bus plate at a second edgethereof and extending therefrom at a third angle; a sixth bus extensionplate joining the second core bus plate at a second edge thereof andextending therefrom at a fourth angle; a fourth core bus plate disposedin parallel with the first, second and third core bus plates; a seventhbus extension plate joined to the fourth core bus plate and disposedparallel to the fifth bus extension plate; and an eighth bus extensionplate joined to the fourth core bus plate and disposed parallel to thesixth bus extension plate.
 7. The apparatus of claim 6, wherein thefirst and fifth bus extension plates extend from the first core busplate in a first direction perpendicular to a plane of the first corebus plate, wherein the second and sixth bus extension plates extend fromthe second core bus plate in a second direction opposite the firstdirection.
 8. The apparatus of claim 7, further comprising: a ninth busextension plate joining the first core bus plate at a third edge thereofand extending therefrom at a fifth angle; a tenth bus extension platejoining the second core bus plate at a third edge thereof and extendingtherefrom at a sixth angle; a fifth core bus plate arranged in parallelwith the first, second, third and fourth core bus plates; an eleventhbus extension plate joined to the fifth core bus plate and disposedparallel to the ninth bus extension plate; and a twelfth bus extensionplate joined to the fifth core bus plate and disposed parallel to thetenth bus extension plate.
 9. The apparatus of claim 8, wherein thefirst, fifth and ninth bus extension plates extend from the first corebus plate in the first direction and wherein the second, sixth and tenthbus extension plates extend perpendicularly from the second core busplate in the second direction.
 10. The apparatus of claim 8, wherein thethird, fourth and fifth core bus plates are disposed between the firstand second core bus plates.
 11. The apparatus of claim 6, wherein thethird and fourth core bus plates are disposed between the first andsecond core bus plates.
 12. The apparatus of claim 1, furthercomprising: a first semiconductor switching device electricallyconnected to ends of the first and third bus extension plates; and asecond semiconductor switching device electrically connected to ends ofthe second and fourth bus extension plates.
 13. The apparatus of claim12, comprising a power converter circuit including the first and secondsemiconductor devices, wherein the first core bus plate and the firstbus extension plate are components of a first DC bus of the powerconverter circuit, wherein the second core bus plate the second busextension plate are components of a second DC bus of the power convertercircuit, and wherein the third core bus plate, the third bus extensionplate and the fourth bus extension plate are components of an input busand/or an output bus of the power converter circuit.
 14. The apparatusof claim 13, further comprising: a first capacitor electricallyconnected to the first bus core plate; and a second capacitorelectrically connected to the second bus core plate.
 15. The apparatusof claim 14, further comprising: a fifth bus extension plate joined tothe first bus core plate, extending at an angle therefrom andelectrically connected to a first terminal of the first capacitor; asixth bus extension plate joined to the second bus core plate, extendingat an angle therefrom and electrically connected to a first terminal ofthe second capacitor; and a common plate parallel to the fifth and sixthbus extension plates and electrically connected to second terminals ofthe first and second capacitors, wherein the third bus core plate has aportion extending between the fifth and sixth bus extension plates andthrough an opening in the common plate. 16-20. (canceled)